Macsyma’s General Simplifier: Philosophy and Operation
by Richard Fateman,
first published in the Macsyma Users Conference, Washington D.C. 1979, in: MUC-79, 563-582.
Notes have been added to the original paper by the author from today's perspective.
A subsection that was not written as of 1979 has also been added in 2017.

Mathematical
Modeling and Simulation by Kai Velten
Kai Velten: Mathematical Modeling and Simulation, Wiley-VCH,
2009.http://books.google.com/books?id=Czp1N5UWpyEC
A book on modeling and simulation exclusively based on open
source software. It includes many examples from such diverse
fields as biology, ecology, economics, medicine, agricultural,
chemical, electrical, mechanical, and process
engineering. Requiring only little mathematical prerequisite
in calculus and linear algebra, this lucidly written text is
accessible to scientists, engineers, and students at the
undergraduate level. The book addresses a broad range of
models from elementary statistical models to ODE and PDE
models. The reader is introduced into CAELinux, Calc,
Code-Saturne, Maxima, R, and Salome-Meca.

Other documents

The Maxima Book
This is a very incomplete and in some places out of date user
oriented manual. It is a work in progress, but is provided
here in the hope it might be useful.
Update: This new version isn't all that different, but it has
been updated a bit with regards to plotting and a couple other
minor changes. Emaxima and install docs have not been updated
yet. Mathematical content is essentially unchanged. Pictures
should be of slightly better quality.